Production of alkyl aromatic sulfonic acids and their salts



Patented Sept. 11, 1951 PRODUCTION OF ALKYL AROMAT IC SUL- I FONIC ACIDS AND THEIR SALTS Ivor G. Nixon, The Hague, Netherlands, assignor to Shell Development Company, San Francisco, Calif a corporation of Delaware No Drawing. Application May 26, 1948, Serial No,

29,415. In the Netherlands May 30, 1947 This invention relates to the production of surface-active alkyl aromatic sulfonic acids having at least nine carbon atoms in an alkyl group and salts thereohand deals with an improved method of producing said compounds in a more advantageous 'form for use as detergents, wetting agents and the like from cheap, readily available starting materials previously considered unsuitable for the production of good quality products of this type.

It is known that the'aromatic sulfonic acids substituted by a high-molecular, aliphatic group and their salts have capillary-active properties making them suitable for use as cleansing agents, wetting agents, dispersing agents and the like. Various processes have already been proposed for the manufacture of such compounds, comprising in the first place the introduction of a high-molecular alkyl group into aromatic hydrocarbons and the subsequent sulfonation of the alkyl aromatics obtained. The introduction of the alkyl group may be eifected by condensing the aromatic hydrocarbons, in the presence of a suitable condensing agent, with an unsaturated aliphatic hydrocarbon or aliphatic halogenated hydrocarbon containing more than 8 carbon atoms to the molecule. In these processes when alkenes were used as initial material for the formation of the alkyl aromatics, these alkenes were applied in apure or concentrated form. For this purpose they had to be obtained in a special manner from mostly rather costly and not readily available or specially composed initial material, for example by dehydration of the fatty alcohol obtained by catalytic hydrogenation of fatty oils, catalytic dehydrogenation of high-molecular saturated hydrocarbons, cracking of parafiln wax or other hydrocarbon material rich in normal parafiins, dehydrohalogenation of halogenated hydrocarbons or polymerization of lower alkenes.

Now it was found that salts of alkylated aromatic sulfonic acids or products containing such salts, which have excellent capillary-active properties, may be very advantageously produced by alkylating monocyclic aromatic hydrocarbons, particularly benzene or toluene, or mineral oil extracts substantially consisting of these substances, with a fraction obtained from a cracked product of hydrocarbonaceous material having a boiling range between the boiling point or the maximum boiling range of the aromatic material and the minimum boiling range of the alkylation product, which fraction contains only a relatively small percentage, i. e. between 10% and 40%, preferably 15 %-30%, of alkenes, in the presence of concentrated sulfuric acid, sulfonating the alkylate-containing reaction mixture thus oh- Claims. (01. 260-505) tamed-after removal of the acid phase and separation of the non-converted hydrocarbonsand subsequently neutralizing the sulfonic acids formed. The preferred initial material is a cracked fraction, the alkenes of which contain 12 carbon atoms tothe molecule on an average.

The alkylation reaction has been found to proceed smoothly without substantial side reactions and to result in the formation of alkyl aromatics, which, in view of the low alkene content of the cracked distillate fraction used, is a surprising phenomenon, the more so as an excessive portion of the alkenes might have been expected to be converted into polymeriaztion products and sulfuric acid esters, and into alkylation products with the isoparaffins present in the cracked fraction.

The special importance of the present process consists in the fact that the hydrocarbon fraction used as alkene source may be derived from any normal cracked product obtained according to the usual methods by thermal or catalytic cracking of hydrocarbon material, such as mineral oils and mineral oil products, particularly fuel oil and similar heavy fractions, so that no expensive initial material is required forthe manufacture of the desired products. As a rule cracked fractions derived from crude petroleum oils of the paraffinic type yield final products with particularly favorable properties.

In the alkylation it is advisable to apply a substantial excess of benzene or toluene or other monocyclic aromatic hydrocarbon over the quantity theoretically required for the formation of alkyl aromatics, since it has been found that undesirable side reactions are thus avoided to a considerable extent. The process is preferably carried out with a molecular ratio of aromatic to alkene of at least 5:1 preferably about 10:1 to :1.

An important advantage of the process according to the invention consists in that it is eminently suitable to be carried out continuously; in fact, in view of the boiling range of the cracked fraction used, both the excess of aromatic and the non-converted hydrocarbons from the cracked fraction can be readily separated from the alkylate mixture obtained in the alkylation, so that the excess of aromatics can be recycled.

Although as preferred aromatics use is made of benzene or toluene, most preferably in a substantially pure form, other monocyclic aromatics,

such as ethyl benzene, cumene and the like may also be employed. Other substances to be used are mineral oil extracts substantially consisting of such aromatics, for example the fractions of Edeleanu extract of kerosene boiling below about 200 C.

The cracked fractions preferably used in the process according to the invention are those in which the alkenes present contain on an average 12 carbon atoms to the molecule and substantially consist of dodecenes, with only a small percentage, preferably not more than 10%, of other high-molecular alkenes, such as the Clo-C11 and the Cl3-C14 alkenes, in addition. In this connection it is to be recommended to use cracked fractions distilling completely be- .tween 170 C. and 230 C., since these generally yield final products with better properties than those obtained when cracked fractions containing constituents boiling below 170 C. or above 230 C. are used.

However, if desired, use may also be made of cracked fractions, the alkenes of which contain on an average less or more than 12 carbon atoms, for example 10 or 14 carbon atoms, provided these cracked fractions do not have boiling ranges overlapping those of the aromatic material and the alkylate to be formed.

Before the cracked fraction is used for the alkylation, it is desirable to remove any alkadienes or other highly reactive constituents which may cause undesirable by-products to be formed. This may be effected by a treatment with a small quantity, for example 1% to 2%, of concentrated sulfuric acid or some other refining agent. The use of a cracked fraction thus pre-refined presents the advantage that during the alkylation the concentration of the sulfuric acid used as catalyst decreases less rapidly, so ..that it can be used for a longer period.

It was found that in order to repress as much as possible the occurrence of undesirable side reactions, such as polymerization and formation of more highly alkylated aromatics, e. g. didodecyl benzene, during the alkylation, the concentration ofthe sulfuric acid used should not be too high. Use is preferably made of sulfuric acid of about 88% to 92% concentration, most preferably 90% sulfuric acid.

The alkylation stage of the process according to the invention is preferably carried out at comparatively low temperatures, e. g. from C. to C. Temperatures above room temperature, e. g. 30 C. to 40 C., have been found less suitable since the products thus obtained generally have a relatively high content of alkyl esters, which may cause difiiculties, such as troublesome emulsification, during the further processing of the reaction mixture, while the concentration of the sulfuric acid used also decreases more rapidly than at lower temperatures, so that it has to be renewed sooner.

The quantity of sulfuric acid used in the alkylation, which varies with the other reaction conditions, is in general rather large. If the concentration of the acid is 90%, the volume ratio of acid to the total quantity of aromatics and alkenes may, for example, be between 09:1 and 12:1, preferably about 1:1.

It is essential for a smooth formation of the desired alkyl aromatics that a very intimate con-. tact should be brought about between the hydrocarbon phase and the sulfuric acid phase, which may be attained by vigorous stirring or. in any other suitable manner. It presents particular advantages to carry out the conversion continuously in a reactor equipped with perforated plates, through which the mixture of hydrocarbons and sulfuric acid in the emulsified state is cycled with great speed via a recirculation conduit, while fresh hydrocarbon mixture and sulfuric acid are charged at one or more points of the cycle and a portion of the reaction mixture corresponding with the fresh charges is drawn off at another point of the cycle. In order to keep the concentration of the acid in the system at the desired level, part of the recycled acid phase is preferably replaced by fresh acid of higher concentration.

The reaction period is preferably so chosen that no or substantially no unconverted alkenes are left in the alkylate-containing reaction mix-.

ture, for which about I to 2 hours will gen-- erally sufiice. Sometimes, however, considerably, shorter reaction periods, e. g. 30 minutes, are

sufficient.

When the alkylation is completed, the alkylatecontaining hydrocarbon phase and the acid phase into which the reaction mixture is split up are separated from each other, for example by decanting or centrifugation, upon which the hydrocarbon phase is subjected to a hydrolytic treatment with aqueous lye or some other strong base, preferably at elevated temperature, for example 150 C. to 160 C., in order to decompose any neutral and acid sulfuric acid esters present.

The excess of aromatics as well as the hydrocarbons of the cracked fraction not converted in the alkylation are removedfrom the alkylatecontaining hydrocarbon phase by fractional distillation. The excess of aromatics can be separated from the unconverted hydrocarbon and returned to the alkylation. The remaining higher boiling portion, the initial boiling point of which corresponds approximately with, or will be higher than, the final boiling point of the cracked fraction used and which contains, besides alkyl aromatics, also other higher molecular products formed during the alkylation, such as isoparaifin alkylates and polymers, is subsequently sulfonated. During this sulfonation the alkyl aromatics are converted into sulfonic acids, while the other components of the alkylate fraction remain unchanged Instead of immediately neutralizing the sulfonation mixture, it was found to be advisable first to remove the unchanged constituents of the alkylate fraction, which can readily be attained because on completion of the sulfonation the said constituents are separated off from the sulfonic acid-containing acid phase as a separate liquid layer. The quantity of this unsulfonatable portion of the alkylation product may vary considerably according to the origin of the alkylation product; in general it amounts to about 10% to 30% of the volume of the alkylate.

In the process according to the invention the whole of the alkylation product freed from excess aromatics and non-converted hydrocarbons is preferably subjected to the sulfonation, since in general the highest yields of the desired sulfonic acids are thus obtained.

If desired, however, it is also possible to separate a. relatively narrow fraction from the alkylation product in question, for example, a fraction boiling at a pressure of 25 mm. between C. and C. and completely or substantially completely consisting of alkyl aromatics, and sulfonate only this fraction, as a result of which no or substantially no unsulfonatable constituents are left behind. However, in this way not all the alkyl aromatics formed may beconverted into sulfonic acids, since a quantitative separation of the alkyl aromatics from the other hydrocarbons present therewith practically cannot'be realized by fractionation, since the preceding and the subsequent fractions are always found to contain a more or less considerable percentage of alkyl aromatics. The sulfonation ofa narrow fraction of the alkylation product may be of advantage in so far that sometimes final products may thus be obtained with slightly better properties than the sulfonates obtained from the whole of the alkylate. One advantageous method of obtainin the alkyl aromatics in purer form without loss in yield is by separating the alkyl aromatics from the iso-paraflin alkylates and polymers of the same boiling range by selective extraction with a suitable solvent, e. g. furfural, sulfolane, dichlorethyl ether, etc., preferably after a mild hydrogenation treatment to selectively saturate the polymers.

In the process according to the invention the sulfonation is preferably carried out with sulfuric acid of at least 97%, which is used in an excess with respect to the alkyl aromatics to be sulfonated. With increasing acid concentration the duration of the sulfonation can be considerably curtailed; thus, when sulfuric acid of 98% con centration is used, the reaction will take about 8 hours, While with 100% acid, the other reaction conditions being the same, the sulfonation takes less than 1 hour. The sulfonation may be carried out at room temperature as well as lowered or elevated temperature. Preferably it is carried out at moderately elevated temperatures up to about 40 C. to 45 C., since in that case slightly higher yields are usually obtained than at lower temperatures. As a rule temperatures above about 50 C. are not considered desirable, since these may give rise to the formation of darkcolored products.

The quantity of the sulfuric acid used in excess during the sulfonation may vary appreciably. The larger this quantity, the lower will bethe percentage of active substance and thehigher the percentage of inorganic sulfate in the product obtained by the neutralization of the reaction mixture. As a rule the ratio is so chosen that 1 volume sulfuriciacid is present to every volume of alkylate. If desired, smaller or larger volume ratios may, however, also be applied, e. g. about 0.8 to 1.25 volumes of sulfuric acid per volume of hydrocarbon.

During the sulfonation the reaction components should be properly mixed. The sulfonation is preferably carried out continuously; for this purpose use may advantageously be made of a similar apparatus to that used in the continuous alkylation. the mixture of the hydrocarbons to be sulfonated and sulfuric acid being cycled through one or more reactors equipped with perforated plates while feeding fresh hydrocarbons and sulfuric acid, andan equivalent amount of the reaction mixture thus formed being drawn off. The sulfonation may advantageously be carried out in two stages in a system of two such reactors, sulfuric acid of 97 %-l% being charged to the first reactor and fuming sulfuric acid of about 5% to 30% free sulfur trioxide content being charged to the second reactor.

In order to prevent any undesirable decrease of the acid concentration, absorption of water vapor should be avoided, and in this connection it is advisable to carry out the sulfonation in a system not communicating with the atmosphere.

The reaction mixture obtained in the sulfonation should be freed from any non-sulfonated hydrocarbons present, since thus purer final products are obtained. This removal may be effected by decanting or cntrifugatioil. The mixture is subsequently neutralized, as a result of which the sulfonic acids are converted into sulfonic acid salts and the excess of sulfuric acid into sulfate.

For the neutralization of the reaction mixture any base or other basic-reacting inorganic or organic substance reacting with the sulfonic acids so as to form water-soluble salts may be used. Thus, in order to produce sodium sulfonates, the neutralization is carried out, for example, with the aid of sodium hydroxide or sodium carbonate. Other alkali metal, ammonium, or amine salts of the alkyl aryl sulfonic acids may be similarly produced by substituting the corresponding suitable basic compounds for the sodium compounds mentioned.

The neutralization is preferably carried out in such a manner that the sulfonation mixture is mixed with an aqueous solution of a basic-reacting substance, in particular alkali carbonate, the temperature being kept at about 80 C. to 100 C. When the neutralization was effected by contacting alkali carbonate solution at room temperature with the sulfonation mixture, the products obtained by drying the neutralized mixture were sometimes found, when dissolved in hard water, to produce a turbid solution, which is not the case with the products obtained by neutralization while heating.

It has been found that the degree of acidity at which the neutralization is carried out affects the color and also the smell of the dried final product, in the sense that they deteriorate according as the pH at the end of the neutralization decreases from about 7 to about 3. Itis to be recommended to carry out the neutralization at a pH of 7 to 7.5, since in that case lightcolored final products with a good smell are obtained, which dissolve in hard water. producing a perfectly clear solution with an only very slightly alkaline reaction. The products obtained by neutralization at a pH of 8 or slightly higher also have a satisfactory appearance, but their solutions are highly alkaline, which may sometimes be undesirable.

example a few per cent, of unsulfonated oil,

which was apparently dissolved in the acid phase of the reaction mixture. Although not necessary in order to obtain a final product with desirable properties, the said oil constituents may also be completely or substantially completely removed from the product. The removal of these oil constituents may be brought about very effectively by extracting the neutralized reaction mixture with an organic solvent which is insoluble or substantially insoluble in water, such as, for example, low-boiling hydrocarbons or ether. Instead of extracting the neutralized reaction mixture, one may also apply the extraction to the dry product obtained from it.

The products prepared according to the invention are generally colored only light yellow. Although as a rule this color is not detrimental, the color may, if desired, still be improved by a treatment with a suitable bleaching agent, such as hypochlorites, peroxides and the like.

Dependent on the excess of sulfuric acid used in the sulfonation, the products finally obtained by the process according to the invention contain, besides the sulfonates, a more or less considerable percentage of inorganic or, where organic bases have been used, orgam'c .sulfate. If the sulfonates are desired in a more concentrated form, their concentration can be effected by subjecting the sulfate-containing mixture to a desalting treatment. Thus, itis, for example, possible to obtain sulfonates poorer in salt or practically free from salt by extraction of the dry products with suitable solvents, such as 96% alcohol.

Owing to their particularly favorable capillaryactive and other properties, such as detergent effect, foaming properties, -Wetting power, limeresistance and solubility, the products prepared according to the invention are eminently suitable for use as detergents and wetting agents, especially for textile goods, and further as emulsifying agents or for other purposes where a good capillary-active effect is required. It has been found that the products obtained according to the invention are equivalent and sometimes even, in one or more respects, superior to other synthetic detergents, such as the highly active higher secondary sodium alkyl sulfates. In this connection it is worth mentioning that the products prepared according to the invention, remarkably enough, possess considerably more favorable,

properties, particularly as regards detergent power and wettingpower, than the sulfonates of alkylation products from benzene and a C12 fraction derived from the polymerization of propane.

The process according to the invention is further illustrated by the following example, without being restricted thereto.

Egvample molecular ratio of benzene to alkenes of :1,

1 while stirring vigorously, to sulfuric acid of 89.6%

concentration, the temperature being kept at about C. by cooling. The volume ratio of acid to benzene plus alkenes amounted to 1:1. After a reaction period of about 75 minutes, during which the vigorous stirring was continued, the alkylate layer, the bromine number of which was 0 and the acid number 1.5, was separated from the acid layer, which had an acid concentration of 84.2% and an alkyl sulfate content of only 1%, and hydrolyzed by a treatment with lye at 150 C.-160 C. The alkylate layer, which, besides the alkylation products formed, also contained the excess of benzene and non-converted paraffin hydrocarbons and naphthenes, was then subjected to a fractional distillation, first at atmospheric pressure and then at a pressure of 25 mm. Hg, in order to remove the excess of benzene and non-converted components of the cracked fraction. The fraction distilling over at 25 mm. above 120 C., the weight of which was about 21% of the C12 cracked fraction used, was subsequently sulfonated, while stirring, with an equal volume of sulfuric acid of 99% during about 8 hours at a temperature of 45 C.

Upon completion of the sulfonation the nonconverted hydrocarbons, which had separated off as upper layer from the reaction mixture, were tained. The dry product thus obtained in a quantity of about 60% of the weight of the cracked fraction, which product consisted of 35% active substance and 65% sodium sulfate, is an excellent detergent, which dissolves even in hard water so as to yield a completely clear solution and whose properties, particlarly as regards detergent power and wetting power, are eqivalent or even'superior to those of other synthetic detergents, such as the higher secondary sodium alkyl sulfates.

I claim as my invention:

1. A process for manufacturing water-soluble salts of alkyl aromatic sulfonic acids having detergent and wetting properties, which comprises alkylating a monocyclic aromatic hydrocarbon by reaction with a fraction of petroleum cracking products containing 15% to 30% of alkenes in admixture with branched chain and cyclic hydrocarbons, which fraction has a boiling range between the maximum boiling range of said aromatic hydrocarbon and the minimum boiling range of the alkylation products of said aromatic hydrocarbon with said alkenes, said reaction being effected at 0 C. to 10 C. in the presence of 0.8 to 1.2 volumes of sulfuric acid of to 92% concentration per volume of hydrocarbon while maintaining a molar ratio of said aromatic hydrocarbon to said alkenes of 5:1 to :1, contacting the hydrocarbon phase of the reacted mixture with. an aqueous inorganic base at C. to C., fractionating the thus treated hydrocarbons to separate the unreacted excess of said aromatic hydrocarbon and other hydrocarbons boiling below the minimum boiling temperature of the alkylation products, removing from the alkyl aromatic hydrocarbons obtained non-aromatic hydrocarbons of the same boiling range by extraction with a solvent having a preferential solubility for aromatic hydrocarbons in the presence of parafiins, sulfonating the separated alkyl aromatic hydrocarbons by reaction in two stages with sulfuric acid, having a concentration of 97% to 100% in the first stage and 5% to 30% oleum in the second stage, at a temperature of 20 C. to 50 C., separating unsulfonated hydrocarbons from the product, and neutralizing the alkyl aromatic sulfonic acids thus obtained with an aqueous solution of a base at a temperature of 80 C. to 100 C. and a pH of 7 to 7.5.

2. A process for manufacturing water-soluble salts of alkyl aromatic sulfonic acids having detergent and wetting properties, which comprises alkylating a monocyclic aromatic hydrocarbon of the benzene series having not more than one carbon atom attached to the nucleus by reaction with a fraction of petroleum cracking products containing 15% to 30% of alkenes in admixture with branched chain and cyclic hydrocarbons and boiling entirely between C. and 230 C. in the presence of 0.8 to 1.2 volumes of sulfuric acid of 85% to 92% concentration per volume of hydrocarbons present while maintaining a substantial molar excess of said aromatic hydrocarbons to said alkenes, contacting the hydrocarbon phase of the reacted mixture with aqueous so- 75 dium hydroxide at 150 C. to 160 C., extending the alkyl aromatic hydrocarbon-containing product with a solvent having a preferential solubility for aromatic hydrocarbons in the presence of paraflins to separate non-aromatic hydrocarbons therefrom, sulfonating the higher alkyl benzenes obtained afterseparating therefrom said excess aromatic hydrocarbon and returning the same to said alkylation by reaction in two stages with sulfuric acid of 97% to 100% concentration in the first stage and oleum containing to 30% free sulfur trioxide in the second stage subjecting the sulfonation product to stratification to separate unsulfonated hydrocarbon constituents therefrom, and neutralizing the alkyl benzene sulfonic acids thus obtained with an aqueous solution of a base at a temperature of 80 C. to 100 c.-and a pH of 7 to 7.5

3. A process for manufacturing water-soluble salts of higher alkyl toluene sulfonic acids having 10 to 14 carbon atoms in the higher alkyl group, which comprises alkylating toluene by reacting a fraction of hydrocarbon cracking products containing 15% to 30% of alkenes in admixture with branched chain and cyclic hydrocarbons, said alkenes being substantially of the same number of carbon atoms per molecule within the range of 10 to 14 carbon atoms and containing not more than 10% of alkenes havinga different number of carbon atoms from that of said alkenes, with a substantial molar excess of toluene in the .presence of sulfuric acid, contacting the hydrocarbon phase of the reacted mixture with an aqueous base at 150 C. to 160 0., fractionating the hydrocarbon products of the reaction to separate therefrom a toluene fraction, a fraction of unreacte'd hydrocarbons of approximately theboiling range of said hydrocarbon cracking products, and a higher boiling fraction containing toluene alkylated by said alkenes, returning said toluene to the alkylation reaction, extracting said alkylated toluene fraction with a selective solvent to separate the alkylated toluene from non-aromatic hydrocarbons present therewith, sulfonating said extracted alkylated toluene by reaction in two stages with sulfuric acid of 97% to 100% concentration in the first stage and oleum contain- 18 to 30% free sulfur trioxide in the second stage, separating the resulting alkyl toluene sulfonic acids from unsulfonated hydrocarbon remaining after said sulfonation, and neutralizing said sulfonic acids with an aqueous sodium carbonate solution at a pH of 7 to 7.5.

4. a process of producing a sodium dodecyl benzene sulfonate, which comprises reacting a fraction of hydrocarbon cracking products having an average of 12 carbon atoms per molecule and *containing 10% to 40% of alkenes in admixture with branched chain and cyclic hydrocarbons of which alkenes not more than 10% have a number of carbon atoms per molecule different from 12 with benzene in a ratio of at least 5 moles of benzene per mole of alkenes in the presence of sulfuric acid, contacting the hydrocarbon phase of the reacted mixture with an aqueous base at 150 C. to 160 c., fractionating the hydrocarbon products of the reaction to separate therefrom a benzene fraction. a fraction of unreacted hydrocarbons of approximatel the boiling range of said hydrocarbon cracking products, and a higher boiling fraction containing benzene alkylated by said alkenes, returning said benzene to the alkylation reaction, extracting said alkylated benzene fraction with a solvent selective for aromatic hydrocarbons in the presence of paraflins to separate the alkylated benzene from non-aromatic hydrocarbons present therewith, sulfonating said alkylated benzene by reaction in two stages with sulfuric acid of 97% to 100% tralizing said sulfonic acids with an aqueous sodium carbonate solution at a pH of 7 to 7.5.

5. A process for manufacturing water-soluble salts of alkyl aromatic sulfonic acids having detergent and wetting properties, which comprises treating .a fraction of petroleum cracking products containing 15% to 30% of alkenes in admixture with branched chain and cyclic hydrocarbons, which fraction has a boiling range between the maximum boiling range of said aromatic hydrocarbon and the minimum boiling range of thealkylation products of said aromatic hydrocarbon, with a small amount of sulfuric acid to selectively remove alkadienes therefrom, admixing the treated fraction with an aromatic hydrocarbon of the benzene series having not more than 7 carbon atoms per molecule, in proportions corresponding to a mole ratio of said aromatic hydrocarbon to said alkenes be-' tween 5:1 and 100:1, contacting the mixture with 0.8 to 1.2 volumes of sulfuric acid of 85% to 92% concentration to effect alkylation of said aromatic hydrocarbon by said alkenes, contacting the hydrocarbon phase of the alkylation mixture with aqueous sodium hydroxide at 150 C. to 160 C., extracting the alkyl aromatic hydrocarbon-containing product with a solvent having a preferential solubility for aromatic hydrocarbons in the presence of parafiins to separate non-aromatic hydrocarbons present therefrom, sulfonating the alkyl aromatic-hydrocarbon produced by reaction in two stages with sulfuric acidof 97% to 100% concentration in the first stage and oleum containing 5% to 30% free sulfur trioxide in the second stage, separating from said sulfonation products unconverted hydrocarbon present therewith, and neutralizing the alkyl arcmatic sulfonic acids obtained.

IVOR G. NIXON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 22,548 Brandt Sept. 26, 1944 2,014,766 Isham "Sept. 17, 1935- 2,106,521 Deanesly Jan. 25, 1938 2,161,174 Kyrides June 6, 1939 2,232,117 Kyrides Feb. 18, 1941 2,232,118 Kyrides Feb. 18, 1941 2,256,610 Buc Sept. 23, 1941 2,285,390 Brandt June 9, 1942" 2,317,986 Flett May 4. 1943- 2,330,922 Riegler; Oct. 5, 1943 2,364,782 Flett Dec. 12,1944- 2,397,133 Flett Mar. 26, 1946- 2,413,161 Zemer Dec. 24, 1946 2,456,119 Friedman et a1 Dec. 14, 1948 2,467,132 Hunt Apr. 12, 1949 2,477,383 Lewis July 2, 1949- 2,479,120 Johnstone Aug. 16, 1949:

OTHER REFERENCES Ipatieff et al.. Journal Am. Chem. Soc.; vol. 58, (1936), pp. 919-923. 

1. A PROCESS FOR MANUFACTURING WATER-SOLUBLE SALTS OF ALKYL AROMATIC SULFONIC ACIDS HAVING DETERGENT AND WETTING PROPERTIES, WHICH COMPRISES ALKYLATING A MONOCYCLIC AROMATIC HYDROCARBON BY REACTION WITH A FRACTION OF PETROLEUM CRACKING PRODUCTS CONTAINING 15% TO 30% OF ALKENES IN ADMIXTURE WITH BRANCHED CHAIN AND CYCLIC HYDROCARBONS, WHICH FRACTION HAS A BOILING RANGE BETWEEN THE MAXIMUM BOILING RANGE OF SAID AROMATIC HYDROCARBON AND THE MINIMUM BOILING RANGE OF THE ALKYLATION PRODUCTS OF SAID AROMATIC HYDROCARBON WITH SAID ALKENES, SAID REACTION BEING EFFECTED AT 0* C. TO 10* C. IN THE PRESENCE OF 0.8 TO 1.2 VOLUMES OF SULFURIC ACID OF 85% TO 92% CONCENTRATION PER VOLUME OF HYDROCARBON WHILE MAINTAINING A MOLAR RATION OF SAID AROMATIC HYDROCARBON TO SAID ALKENES OF 5:1 TO 100:1, CONTACTING THE HYDROCARBON PHASE OF THE REACTED MIXTURE WITH AN AQUEOUS INORGANIC BASE AT 150* C. TO 160* C., FRACTIONATING THE THUS TREATED HYDROCARBONS TO SEPARATE THE UNREACTED EXCESS OF SAID AROMATIC HYDROCARBON AND OTHER HYDROCARBONS BOILING BELOW THE MINIMUM BOILING TEMPERATURE OF THE ALKYLATION PRODUCTS, REMOVING FROM THE ALKYL AROMATIC HYDROCARBONS OBTAINED NON-AROMATIC HYDROCARBONS OF THE SAME BOILING RANGE BY EXTRACTION WITH A SOLVENT HAVING A PREFERENTIAL SOLUBILITY FOR AROMATIC HYDROCARBONS IN THE PRESENCE OF PARAFFINS, SULFONATING THE SEPARATED ALKYL AROMATIC HYDROCARBONS BY REACT IN TWO STAGES WITH SULFURIC ACID, HAVING A CONCENTRATION OF 97% TO 100% IN THE FIRST STAGE AND 5% TO 30% OLEUM IN THE SECOND STAGE, AT A TEMPERATURE OF 20* C. TO 50* C., SEPARATING UNSULFONATED HYDROCARBONS FROM THE PRODUCT, AND NEUTRALIZING THE ALKYL AROMATIC SULFONIC ACIDS THUS OBTAINED WITH AN AQUEOUS SOLUTION OF A BASE AT A TEMPERATURE OF 80* C. TO 100* C. AND A PH OF 7 TO 7.5. 